This post is for reference purposes for a discussion on the evolution of dynamic brake and air filter configuration on Penn Central GP38s. The photos have been reprinted from the Volume 16 Number 2 of Post, the Penn Central Railroad Historical Society’s publication. I’ve captioned the photos with I think to be the progression of GP38 dynamic brake appearance. PLEASE, correct any errors I’ve made in my assertions.
This last photo shows the modification that was made to earlier production GP38s that didn’t have the paper air filter at the time of their delivery. The original longer dynamic brake blister was simply modified by being truncated in order to make space for the paper filter box. Early production units on Penn Central were retrofitted with this modification over time, so early photos of some early production units will have it appear like the top photo, then at some point the mod was done and the same unit will look like the bottom photo. I’ll try to post some examples.